Pressure responsive operator



March 12, 1963 D. M. PAPA PRESSURE RESPONSIVE OPERATOR Filed April 2,1959 PRESiURE RESlONSlVE OFERATGR Donald M. Papa, Milwaukee, Wis,assignor to Cutler- Hammer, Inc, Milwaukee, Wis, a corporation ofDelaware Filed Apr. 2, 1959, Ser. No. $03,763 1 Ciairn. ill. 137-484)This invention relates to pressure responsive operators and moreparticularly to those for use in the vacuum range.

Pressure responsive operators designed foruse in the vacuum range ofpressure commonly employ two diaphragms, a main diaphragm fortransmitting movement to an operating rod and a second diaphragm toafford a flexible seal about an opening in the vacuum chamber as theoperating rod moves inwardly and outwardly thereof.

Therefore, a principal object, of this invention is to provide animproved pressure responsive controller wherein the necessity ofproviding a second diaphragm to seal the vacuum chamber is eliminated.

\ A further object is to provide a controller of the aforesaid characterin which the vacuum chamber may be evacuated through a pushrod elementpenetrating said vacuum chamber.

Another object is to provide a pressure responsive control device whichis characterized by simplicity of design, low cost of manufacture, andextended operational life.

Other objects and advantages of the invention will hereinafter appear.

In the drawings:

FIGURE 1 is a top plan view of an electric switch controller constructedin accordance with, my invention;

FIG. 2 is an elevational view partly in section taken along lines 2-2 ofFIG. 1 and further schematically illustratingan attached switchmechanism; and

FIG. 3 is an enlarged sectional view of a subassembly shown in FIG. 2.

As best illustrated in PEG. 2, the operator device comprises a diaphragmhousing 19, a pushrod 12, a flexible diaphragm 14, a diaphragm follower16, an annular bearing bushing 18 and a fitting 20. Also shown in FIG. 2are portions of one form of switch mechanism 30 suitably constructed'foroperation by my pressure responsive operator. The cooperation of certainparts of the switch mechanism 30 and the operator will be hereinafterdescribed in detail.

The housing 10 comprises two symmetrically formed, shallow, bell-shapedmembers Ida and itlb. The latter are preferably formed of a metal suchas steel or aluminum. The flanged peripheral portions 10c of members 10aand 1011 are provided with radially spaced apertures 10d, best shown inFIG. 1, which are alined to receive threaded screws 22. Additionalapertures lite and 10 are provided in housing members 18a and 10b,respectively. Apertures ltle are open to the atmosphere, while apertures10 are alined with like dimensioned apertures 32a in switch frame 32 toaccommodate threaded fasteners 24 which secure the housing 10 to theswitch frame 32. Housing member 10a is provided with a central circularopening 10 for receiving a reduced portion Zita of fitting 20. Thebushing 18 has a reduced portion 18a which projects outwardly of housing10 through a central opening 10k in member liib. Fitting 2t) and bushing18 are preferably brazed to their respective housing members 10a and 10bto provide an airtight seal therebetween.

As shown in FIG. 2, diaphragm 14, which is circular and formed of asuitable resilient material, extends transversely of the assembledhousing 10 bisecting the same into an upper chamber 10h and a lowerchamber 103..

The outer periphery of diaphragm 14 is compressively 3,080,8% PatentedMar. 12, 1963 ice sealed between the opposing flanged portions 10c ofhousing members 10a and 10b while the periphery of a central opening 14atherethrough is, as best shown in FIG. 3,

, compressively sealed between an annular flange 12a on pushrod 12 andthe diaphragm follower 16.

As best illustrated in FIG. 3, the pushrod 12 is substantiallycylindrical in shape and may be machined from a single piece of stock. Astepped body portion 12a comprising a portion 12b and an annular flange12c is integrally formed intermediate the ends of the pushrod 12. Thediaphragm follower 16 which comprises a flat, rigid disk overlying agreater portion of diaphragm 14 is permanently secured at its center topushrod 12. As shown in FIG. 3, the inner peripheral wall of thecentrally located opening 164: in the diaphragm follower 16 surroundsthe portion 1212 on the pushrod 12. The diaphragm 14 and diaphragmfollower 16 are compressively held between the annular flange 12c andthe outwardly flared portion 1211 of the portion 12b. The flaringoperation is completed subsequent to assembly of the diaphragm 14 anddiaphragm follower 16 on the pushrod 12 and may be accomplished by ringstaking or peening over the upper surface of the portion 12b.

Toroids or O-rings 26 and 28 are preferably formed of a resilientmaterial, such as neoprene or Buna N synthetic rubber, and may belubricated with pneumatic grease. The annular grooves 12d and 12:: whichare oppositely located outwardly of the midpoint of the pushrod alongits longitudinal axis accommodate the toroids 26 and 28 and preventtheir displacement upon longitudinal movement of the pushrod 12 withinfitting 20 and bearing 18, When the above described parts are properlyassembled as shown in FIG. 2, the grooved portions and 12a of pushrod 12which carry the toroids 26 and 28 are disposed within the alignedopenings 18b and Ztlb of the bearing 18 and the fitting 20,respectively. The toroids are of such dimension to provide a slidingseal between the pushrod and the walls of openings 13b and 2% as thepushrod 12 reciprocates within said openings.

As shown in FIG. 2, a reduced end portion 12 of pushrod 12 extendsupwardly into interfitting engagement with a central opening 34a in thespring gland 34 of the switch mechanism 30.

As best illustrated in FIG. 3, cylindrical bore 12g extends coaxiallythrough the pushrod 12 from the lower end wall 12m thereof to a pointintermediate the annular recess 12d and the annular shoulder 12b.Intersecting the innermost extreme of bore 12 is an aperture 12k whichextends transversely through pushrod 12 and opens into chamber lilh. Itwill be understood that the longitudinal bore 12g and the transverseaperture 12k provide an airtight connection between the interior boreZtic of fitting 2t) and the sealed chamber 10h.

An essential feature of this invention is the elimination of allexterior connections to the vacuum chamber 14th. As shown this result isachieved by providing a passageway through the pushrod 12 itself whichfunctions as a vacuum connectionto the vacuum chamber 10h.

In operation the interior bore Ztic of fitting 20 is connectcd to avessel, pipeline or other enclosure in which a pressure less thanatmospheric is to be created and maintained by a vacuum producingdevice. As a vacuum is created in the interior bore 200 of fitting 29,the pressure in chamber 16h acting upon diaphragm 14 is reduced to lessthan atmospheric. As shown previously, the chamber ltlg opens toatmosphere through the apertures 10a in housing member 10a; therefore,the underside of the flexible diaphragm 14 is continuously subjected toatmospheric pressure. The resulting pressure differential on oppositesides of the-diaphragm 14 tends to flex the latter I V j upwardiy. Thediaphragm iollowerle'is urged upwardly by the underlying diaphrgam 14thereby transmitting a 'force upwardly throughpushrod 12 and springgland 34 against the downward bias of compression spring 36 of theswitch mechanism 3%. As the pressure differential acting upon diaphragmi i-overcomes this downwardbias of spring lid, the pushrod -12. carriesthe spring gland 34 out of engagement with an underlying portion 33a ofthe lever 25% which extends transversely of the switch housing 32,thereby permitting lever 38 to pivot in a counterclockwise directionabout a pivot member 40' in response to the biasing action of spring 42.As lever fis'pivots in'the manner just described, an insulating contactactuator bar 44 attached to the lever 38 moves its associated contractoras intoycir-cuit completing engagement with stationary.

. contacts 48. V, r

As the pressure differential actingupon diaphragm 14 guesses Although myinvention is particularly suitedfor operatron as a vacuum sensingcontrol device,.from the. foregoing description it will be apparent toone skilled in the 7 art that this device is likewise adaptedfor'operation as a positive pressure actuated controller. Furthermore,while the embodiment hereinde-scribed in detail suggests that thecontroller is particularlywell suitedto actuate an electric switchingmechanism, it is' apparent that my invention will perform variousmechanical as well as electrical con-' decreases to a predeterminedvalue, the biasing action of tional diaphragm as a seal between thedriving element of the controller and the switchmechanism housing 32.

' Therefore, the vertical displacement of the pushrod 12 is limited tothe normal distance shownin FIG. 2 between the upper surface oftheflared portion 12a of the pushrod 12 and the lower surface 18c of thebearing 18. This distance is ,such'that the aforedescribed sliding sealbetween the pushrod l2 and thebearing 1'3 and fitting 20 is maintainedwhen the pushrod is moved to its upper limit.

The "afored'escribed embodiment of my invention may be used with manyknown forms of switching mechanisms to translate the verticaldisplacement of the pushrod intoi a switching function. "While one formof such a switch mechanism-has been shown partially in diagrammatic formin FIG. '2, the structural details of an electric switch rnechanisrnwellsuited for operation in response tomy controlling device is disclosed inU.S. Patent No.

trol functions in response to a predetermined pressure differential.

Iclaim: I

In a pressure-responsive operator,- in combination, a diaphragm housingcomprising mating, bell-shaped members, a flexibie diaphragm having itsouter periphery secured between the matingsuriaces of saidbell-shapedmembersto'divide said housing into a first chamber sealed to t eatmosphere and a second chamber open to the at f mosphere, apushrodaxially penetrating the end walls of said housing and saiddiaphragmsealing means between said pushrod and said end wallscomprising resilient toroidal gaskets seatedin annular recesses in saidpushrod, a diaphrag. i follower disk substantially overlying saiddiaphragm in said first chamber and movable therewith, said dish beingrigidly attached at its center point to saidfp'ushrod, a fittingattached jexteriorly of. said second chamber, a vacuum connectionbetween said fitting and said first chamber provided by a longitudinalbore intersected by a transverse aperture in said pushrod, said borecommunieating with said fitting and said aperture communicating withsaid first chamber.

'Refcrencesflited in the file of this patent UNITED STATES PATENTS1,994,835 Sanford et al. Q Mar. 19, 1935' r 2,069,016. Newton ..-Jan.26, 196-7 2,438,723. 7 setter -Mar. 30, 194 8 2,554,266 7 Pauly May 22,:1951 2,655,573. 1 Szwargulskitet al. Oct. 1-3, 1953 2,664,108 VonWeiseDec. 29, 1 953 2,767,277 Wirth Oct.'l6, 1956 2,825,361 Seljos ..'-Mar.4, 1958

